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81.
Takeshi Iwashita Kota Ikehara Takeshi Fukaya Takeshi Mifune 《Numerical Linear Algebra with Applications》2023,30(6):e2512
In this article, we focus on solving a sequence of linear systems that have identical (or similar) coefficient matrices. For this type of problem, we investigate subspace correction (SC) and deflation methods, which use an auxiliary matrix (subspace) to accelerate the convergence of the iterative method. In practical simulations, these acceleration methods typically work well when the range of the auxiliary matrix contains eigenspaces corresponding to small eigenvalues of the coefficient matrix. We develop a new algebraic auxiliary matrix construction method based on error vector sampling in which eigenvectors with small eigenvalues are efficiently identified in the solution process. We use the generated auxiliary matrix for convergence acceleration in the following solution step. Numerical tests confirm that both SC and deflation methods with the auxiliary matrix can accelerate the solution process of the iterative solver. Furthermore, we examine the applicability of our technique to the estimation of the condition number of the coefficient matrix. We also present the algorithm of the preconditioned conjugate gradient method with condition number estimation. 相似文献
82.
Elizabeth A. Proctor Pradeep Kota Andrei A. Aleksandrov Lihua He John R. Riordan Nikolay V. Dokholyan 《Chemical science》2015,6(2):1237-1246
Many cellular functions necessary for life are tightly regulated by protein allosteric conformational change, and correlated dynamics between protein regions has been found to contribute to the function of proteins not previously considered allosteric. The ability to map and control such dynamic coupling would thus create opportunities for the extension of current therapeutic design strategy. Here, we present an approach to determine the networks of residues involved in the transfer of correlated motion across a protein, and apply our approach to rescue disease-causative mutant cystic fibrosis transmembrane regulator (CFTR) ion channels, ΔF508 and ΔI507, which together constitute over 90% of cystic fibrosis cases. We show that these mutations perturb dynamic coupling within the first nucleotide-binding domain (NBD1), and uncover a critical residue that mediates trans-domain coupled dynamics. By rationally designing a mutation to this residue, we improve aberrant dynamics of mutant CFTR as well as enhance surface expression and function of both mutants, demonstrating the rescue of a disease mutation by rational correction of aberrant protein dynamics. 相似文献
83.
Nickel-Impregnated Silica Nanoparticle Synthesis and Their Evaluation for Biocatalyst Immobilization
Reddy Shetty Prakasham G. Sarala Devi Chaganti Subba Rao V. S. S. Sivakumar T. Sathish P. N. Sarma 《Applied biochemistry and biotechnology》2010,160(7):1888-1895
In the present investigation, impact of nickel-impregnated silica paramagnetic particles (NSP) as biocatalyst immobilization
matrices was investigated. These nanoparticles were synthesized by sol–gel route using a nonionic surfactant block co polymer
[poly (ethylene glycol)-block-poly-(propylene glycol)-block-poly (ethylene glycol)]. Diastase enzyme was immobilized on these particles (enzyme-impregnated NSP) as model enzyme and
characterized using Fourier-transform infrared spectroscopy and X-ray crystallography. Analysis of enzyme-binding nature with
these nanoparticles at different physiological conditions revealed that binding pattern and activity profile varied with the
pH of the reaction mixture. The immobilized enzyme was further characterized for its biocatalytic activity with respect to
kinetic properties such as Km and Vmax and compared with free enzyme. Paramagnetic nanoparticle-immobilized enzyme showed
more affinity for substrate compared to free one. The nature of silica and nickel varied from amorphous to crystalline nature
and vice versa upon immobilization of enzyme. To the best of our knowledge, this is the first report of its kind for change
of nature from one form to other under normal temperatures upon diastase interaction with NSP. 相似文献
84.
Takashi Komine Kota Takahashi Hiroshi Murakami Ryuji Sugita 《Journal of magnetism and magnetic materials》2010,322(19):2969-2972
In this study, the effect of exchange stiffness constant on current-driven domain wall motion in nanowires with in-plane magnetic anisotropy (IMA) and perpendicular magnetic anisotropy (PMA) has been investigated using micromagnetic simulation. The critical current density in a nanowire with IMA decreases as the exchange stiffness constant decreases because the domain wall width at the upper edge of the nanowire narrows according to the decrease of the exchange stiffness constant. On the other hand, the critical current density in a nanowire with PMA slightly decreases contrary to that of IMA although the domain wall width reasonably decreases as the exchange stiffness constant decreases. The slight reduction rate of the critical current density is due to the increase of the effective hard-axis anisotropy of PMA nanowire. 相似文献
85.
Rao KS Rani SU Charyulu DK Kumar KN Lee BK Lee HY Kawai T 《Analytica chimica acta》2006,576(2):177-183
A novel approach for immobilization of probe oligonucleotides that uses zirconium phosphate modified silica nanoparticles is proposed. The surface modification of nanoparticles was carried out in two stages. Initially binding of Zr4+ to the surface of silica nanoparticles and later treated with phosphoric acid for terminal phosphate groups. Oligonucleotide probes modified with amine group at 5'-end were strongly binds to the phosphate terminated silica nanoparticles with imidazole in presence of 0.1 mol L(-1) EDC [N-ethyl-N'-(3-dimethylaminopropyl) carbodiimide], as phosphate groups are more reactive towards amine group. Various studies, i.e., synthesis of silica nanoparticles, their surface modification, probe immobilization, measurement of hybridization and effect of bovine serum albumin (BSA) were carried out during optimization of reaction conditions. The significant reduction in the background signal was observed by treating the probe modified silica nanoparticles with bovine serum albumin prior to hybridization. The probe modified silica nanoparticles were retained their properties and the hybridization was induced by exposure of single-stranded DNA (ssDNA) containing silica nanoparticles to the complementary DNA in solution. The decrease in the fluorescence signal for one mismatch and three mismatch was observed upon hybridization of probe with target DNAs, while there was no response for the random target ssDNA under the same experimental conditions. The intensity of fluorescence signal was linear to the concentration of target DNA ranging from 3.9 x 10(-9) to 3.0 x 10(-6)mol L(-1). A detection limit of 1.22 x 10(-9) mol L(-1) of oligonucleotides can be estimated. The proposed hybridization assay is simple and possesses good analytical characteristics and it can provide an effective and efficient route in the development of DNA biosensors and biochips. 相似文献
86.
We propose and study a system of evolution equations. This is an abstract formulation of problems arising in non-isothermal
phase transitions. We consider time-dependent constraints on the unknown functions. Thus the problem yields a system of parabolic
variational inequalities. We prove the existence of a solution in a general framework, and then apply the abstract result
to some models of phase transitions. 相似文献
87.
Kota Thirumala Prasad A.K. Chandra Kollipara Mohan Rao 《Journal of organometallic chemistry》2010,695(5):707-2022
Reactions of 3,6-bis(2-pyridyl)-4-phenylpyridazine (Lph) with [(η6-arene)Ru(μ-Cl)Cl]2 (arene = C6H6, p-iPrC6H4Me and C6Me6), [(η5-C5Me5)M(μ-Cl)Cl]2, (M = Rh and Ir) and [(η5-Cp)Ru(PPh3)2Cl] (Cp = C5H5, C5Me5 and C9H7) afford mononuclear complexes of the type [(η6-arene)Ru(Lph)Cl]PF6, [(η5-C5Me5)M(Lph)Cl]PF6 and [(Cp)Ru(Lph)(PPh3)]PF6 with different structural motifs depending on the π-acidity of the ligand, electronic properties of the central metal atom and nature of the co-ligands. Complexes [(η6-C6H6)Ru(Lph)Cl]PF61, [(η6-p-iPrC6H4Me)Ru(Lph)Cl]PF62, [(η5-C5Me5)Ir(Lph)Cl]PF65, [(η5-Cp)Ru(PPh3)(Lph)]PF6, (Cp = C5H5, 6; C5Me5, 7; C9H7, 8) show the type-A binding mode (see text), while complexes [(η6-C6Me6)Ru(Lph)Cl]PF63 and [(η5-C5Me5)Rh(Lph)Cl]PF64 show the type-B binding mode (see text). These differences reflect the more electron-rich character of the [(η6-C6Me6)Ru(μ-Cl)Cl]2 and [(η5-C5Me5)Rh(μ-Cl)Cl]2 complexes compared to the other starting precursor complexes. Binding modes of the ligand Lph are determined by 1H NMR spectroscopy, single-crystal X-ray analysis as well as evidence obtained from the solid-state structures and corroborated by density functional theory calculations. From the systems studied here, it is concluded that the electron density on the central metal atom of these complexes plays an important role in deciding the ligand binding sites. 相似文献
88.
Mandal S Sathish M Saravanan G Datta KK Ji Q Hill JP Abe H Honma I Ariga K 《Journal of the American Chemical Society》2010,132(41):14415-14417
Although artificial capsule structures have been thoroughly investigated, functionality at the surfaces of their interiors has been surprisingly overlooked. In order to exploit this aspect of capsular structure, we here report the breakthrough fabrication of metallic (platinum) microcapsules with sufficient accessibility and electroactivity at both interior and exterior surfaces (open-mouthed platinum microcapsules), and also we demonstrate improvements in electrochemical and catalytic functions to emphasize the practical importance of our concept. The open-mouthed platinum microcapsules were prepared by template synthesis using polystyrene spheres, where surface-fused crystalline nanoparticles formed a capsule shell. Subsequent removal of the polystyrene spheres induced formation of mouth-like openings. The open-mouthed platinum microcapsules exhibit a substantial increase of their electrode capability for methanol oxidation and catalytic activities for carbon monoxide (CO) oxidation. Notably, activity loss during CO oxidation due to undesirable particle agglomeration can be drastically suppressed using the open-mouthed microcapsules. 相似文献
89.
[structure: see text] A novel diterpene, (-)-axinyssene, was isolated from the Japanese marine sponge Axinyssa sp. The structure of (-)-axinyssene was determined on the basis of spectroscopic and synthetic evidence to be 1-methyl-4-[(4E)-5',9'-dimethyl-1'-methylene-4',8'-decadienyl]-(4S)-cyclohexene. (-)- and (+)-axinyssene showed mild cytotoxicity against acute promyelocytic leukemia, HL-60 cells. 相似文献
90.
A novel method for synthesis of silica nanoparticles 总被引:7,自引:0,他引:7
Rao KS El-Hami K Kodaki T Matsushige K Makino K 《Journal of colloid and interface science》2005,289(1):125-131
A sequential method has been used, for the first time, to prepare monodisperse and uniform-size silica nanoparticles using ultrasonication by sol-gel process. The silica particles were obtained by hydrolysis of tetraethyl orthosilicate (TEOS) in ethanol medium and a detailed study was carried out on the effect of different reagents on particle sizes. Various-sized particles in the range 20-460 nm were synthesized. The reagents ammonia (2.8-28 mol L(-1)), ethanol (1-8 mol L(-1)), water (3-14 mol L(-1)), and TEOS (0.012-0.12 mol L(-1)) were used and particle size was examined under scanning electron microscopy and transmission electron microscopy. In addition to the above observations, the effect of temperature on particle size was studied. The results obtained in the present study are in agreement with the results observed for the electronic absorption behavior of silica particles, which was measured by UV-vis spectrophotometry. 相似文献